从MainActivity（开始屏幕）切换到播放屏幕活动。意图崩溃应用程序

Question

所以我一直在寻找如何修复这个应用程序。但我似乎并不了解它为什么会崩溃。我的代码与所有关于同一问题的其他问题相同，但它似乎仍然无效。这是我的Start screen.class文件的副本：

package org.concordacademy.hangman;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;

public class MainActivity extends Activity {

    private final String MA = "Main Activity";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Log.i(MA, "Loading Title Screen.");
    }

    // This Below Starts the Intent Push to the "Play Screen"

    public void playGame(View v) {
        Log.i(MA, "Starting Game");
        Intent pushToPlayScreen = new Intent(MainActivity.this, PlayScreen.class);
        startActivity(pushToPlayScreen);

    }

    @Override
    public void onStart() {
        super.onStart();
        Log.i(MA, "onStart");

    }

    @Override
    public void onResume() {
        super.onResume();
        Log.i(MA, "onResume");
    }

    @Override
    public void onPause() {
        super.onPause();
        Log.i(MA, "onPause");
    }

    @Override
    public void onStop() {
        super.onStop();
        Log.i(MA, "onStop");
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        Log.i(MA, "onDestroy");
    }

}

这是我的Playscreen.class文件：

package org.concordacademy.hangman;


import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;

public class PlayScreen extends Activity {

    // The String Below will tell Console/LogCat the processes of The PlayScreen Activity

    private final String PS = "Play Screen";

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_playscreen);
        Log.i(PS, "Loading Play Screen.");
    }

    // Read Text File entitled wordsEn.txt 
        public String readFromFile() {
            String words = "";
            // Array List That Words being added to
            ArrayList<String> wordLineArray = new ArrayList<String>();

            try { 
                InputStream inputstream = openFileInput("wordsEn.txt");
                if (inputstream != null) {
                    InputStreamReader inputStreamReader = new InputStreamReader(inputstream);
                    BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
                    String receiveString = "";
                    StringBuilder stringBuilder = new StringBuilder();

                    while ( (receiveString = bufferedReader.readLine()) != null ) {
                        wordLineArray.add(receiveString);
                        stringBuilder.append(receiveString);
                    }
                    inputstream.close();
                    words = stringBuilder.toString();
                }

            }
            catch (FileNotFoundException e) {
                Log.e("login activity", "File not found: " + e.toString());
            } catch (IOException e) {
                Log.e("login activity", "Can not read file: " + e.toString());
            }

            return words;
        }

}

这是我的清单文件：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="org.concordacademy.hangman"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="16"
        android:targetSdkVersion="19" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_hangmanicon"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" 
        android:debuggable="true">
        <activity android:name=".MainActivity" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity android:name=".PlayScreen" >
        </activity>
    </application>

</manifest>

这是我的MainActivity Layout.XML文件：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/LinearLayout1"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center_horizontal"
    android:orientation="vertical"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="50dp"
        android:gravity="center_horizontal"
        android:text="@string/title"
        android:textSize="50sp" />

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="250dp"
        android:text="@string/ButtonTitle"
        android:onClick="playGame" />

</LinearLayout>

这是我的Playscreen Layout.XML文件：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <fragment
        android:id="@+id/fragment1"
        android:name="org.concordacademy.hangman.GallowsFragment"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

</LinearLayout>

绞架碎片（由合作伙伴添加）类别代码。

package org.concordacademy.hangman;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

public class GallowsFragment extends Fragment {

    View view;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {

        view = inflater.inflate(R.layout.activity_gallows, container, false);
        return view;

    }

}

堆栈跟踪（LogCat，致命异常错误）

03-01 11:11:04.921: E/AndroidRuntime(562): FATAL EXCEPTION: main
03-01 11:11:04.921: E/AndroidRuntime(562): java.lang.RuntimeException: Unable to start activity ComponentInfo{org.concordacademy.hangman/org.concordacademy.hangman.PlayScreen}: android.view.InflateException: Binary XML file line #7: Error inflating class fragment
03-01 11:11:04.921: E/AndroidRuntime(562):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2129)
03-01 11:11:04.921: E/AndroidRuntime(562):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2154)
03-01 11:11:04.921: E/AndroidRuntime(562):  at android.app.ActivityThread.access$700(ActivityThread.java:146)
03-01 11:11:04.921: E/AndroidRuntime(562):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1260)
03-01 11:11:04.921: E/AndroidRuntime(562):  at android.os.Handler.dispatchMessage(Handler.java:99)
03-01 11:11:04.921: E/AndroidRuntime(562):  at android.os.Looper.loop(Looper.java:137)
03-01 11:11:04.921: E/AndroidRuntime(562):  at android.app.ActivityThread.main(ActivityThread.java:4949)
03-01 11:11:04.921: E/AndroidRuntime(562):  at java.lang.reflect.Method.invokeNative(Native Method)
03-01 11:11:04.921: E/AndroidRuntime(562):  at java.lang.reflect.Method.invoke(Method.java:511)
03-01 11:11:04.921: E/AndroidRuntime(562):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1043)
03-01 11:11:04.921: E/AndroidRuntime(562):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:810)
03-01 11:11:04.921: E/AndroidRuntime(562):  at dalvik.system.NativeStart.main(Native Method)
03-01 11:11:04.921: E/AndroidRuntime(562): Caused by: android.view.InflateException: Binary XML file line #7: Error inflating class fragment
03-01 11:11:04.921: E/AndroidRuntime(562):  at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:710)
03-01 11:11:04.921: E/AndroidRuntime(562):  at android.view.LayoutInflater.rInflate(LayoutInflater.java:752)
03-01 11:11:04.921: E/AndroidRuntime(562):  at android.view.LayoutInflater.inflate(LayoutInflater.java:495)
03-01 11:11:04.921: E/AndroidRuntime(562):  at android.view.LayoutInflater.inflate(LayoutInflater.java:397)
03-01 11:11:04.921: E/AndroidRuntime(562):  at android.view.LayoutInflater.inflate(LayoutInflater.java:353)
03-01 11:11:04.921: E/AndroidRuntime(562):  at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:318)
03-01 11:11:04.921: E/AndroidRuntime(562):  at android.app.Activity.setContentView(Activity.java:1920)
03-01 11:11:04.921: E/AndroidRuntime(562):  at org.concordacademy.hangman.PlayScreen.onCreate(PlayScreen.java:24)
03-01 11:11:04.921: E/AndroidRuntime(562):  at android.app.Activity.performCreate(Activity.java:5185)
03-01 11:11:04.921: E/AndroidRuntime(562):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1094)
03-01 11:11:04.921: E/AndroidRuntime(562):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2093)
03-01 11:11:04.921: E/AndroidRuntime(562):  ... 11 more
03-01 11:11:04.921: E/AndroidRuntime(562): Caused by: java.lang.ClassCastException: org.concordacademy.hangman.GallowsFragment cannot be cast to android.app.Fragment
03-01 11:11:04.921: E/AndroidRuntime(562):  at android.app.Fragment.instantiate(Fragment.java:577)
03-01 11:11:04.921: E/AndroidRuntime(562):  at android.app.Fragment.instantiate(Fragment.java:552)
03-01 11:11:04.921: E/AndroidRuntime(562):  at android.app.Activity.onCreateView(Activity.java:4828)
03-01 11:11:04.921: E/AndroidRuntime(562):  at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:686)
03-01 11:11:04.921: E/AndroidRuntime(562):  ... 21 more

如果您知道如何解决，请回复。我有一个项目将于下周到期，如果这个意图不起作用，那就太糟糕了。

Answer 1

您延长Activity。如果您打算使用支持库中的Fragment，则必须扩展FragmentActivity，这是所有基于支持的片段的基类。 （对于低于11的api级别）

替换

import android.support.v4.app.Fragment;

通过这个

import android.app.Fragment

注意：

你的min sdk在清单中是16，所以不需要扩展FragmentActivity并使用基于支持的片段。

Answer 2

片段导入存在问题。 GallowsFragment定义为SupportFragment，而在XML中定义为Fragment。特别需要编辑导入：

import android.support.v4.app.Fragment;

应该是：

import android.app.Fragment;